This invention relates to a feeding device for a printed circuit board useful particularly for high fidelity, low noise amplifiers etc., and also relates to a novel feeding element used therein.
A conventional printed circuit board comprises a wiring circuit of stringy-made foil which is prepared by placing a copper foil on an insulating board and etching the so laminated copper foil. Generally, the thickness of the copper foil is as thin as several tens to several hundreds micronmeters. When the thinner foil is employed for a printed circuit board, however, there occurs non-linear distortion on the printed circuit that employs the so treated foil as a line. For this reason, a printed circuit used in high-quality audio equipment comprises, for example, sufficiently thicker foil to avoid the non-linear distortion. The employment of such thicker foil, however, requires a very long time for the etching, in other words, for forming the circuit. This inevitably results in a circuit of extremely high price. There is also another principal non-linear distortion disturbing the amplifier, occurring on another portion than the above-mentioned circuit. That is a power source being connected to the circuit, and it is ascertained that the non-linear distortion occurring in an electrolytic capacitor provided to the power source particularly causes cross modulation on either of signals, resulting in lowering extremely the quality of the amplifier.
For another example, in digital signal devices such as computers, the power feeding line on the printed circuit board is supplied with deposited feeding bus bars having distributed capacities. In this case, the distributed capacity per unit length of the bus bar is as low as 500 PF/100 mm. at the maximum. This means that enough by-pass function can not be achieved when such system is employed in the audio band. In addition, since this system utilizes such material of high dielectric constant as film of plastic material, ceramic material, etc., as the dielectric material providing the distributed capacity, the non-linear distortion of the line increases due to the dissipation factor of the material and enhances the equivalent series resistance to enlarge the internal loss. These phenomena result in an increase of the distortion among the circuits utilizing the common power line. Therefore, such bus bar cannot be employed in high-quality audio equipment.
This invention, accordingly, provides a feeding device for a printed circuit board useful particularly for such low-noise electric equipment as high quality audio and video equipment, and a feeding element used therein, both of which comprises providing an improved feeding means to a portion constituting a common power line in plural circuits on a printed circuit board and also providing a novel feeding element of large capacity and low loss pertinent to the feeding means, thereby decreasing as far as possible the non-linear distortion occurring in the power source.
It is a principal object of this invention to provide a feeding device and a feeding element that are able to minimize the non-linear distortion occurring on a power line in an electrical device utilizing a printed circuit board.
It is another object of this invention to decrease cross modulation occurring among the circuits using a common line in an electrical device utilizing a printed circuit board, by constituting the power line on the printed circuit board with distributed capacity elements of low loss.
It is still another object of this invention to provide a feeding element of low loss and large distributed capacity that is able to minimize the distortion occurring among the circuits using a common power line in an electrical device utilizing a printed circuit board.